Grinding machine



March 5, 1963 P. DUMMEL 3,079,733

GRINDING MACHINE Filed Oct. 28, 1957 INV EN TOR Pa u/ Dz'z'mzzz 2/ ATTORNEYS gal This invention relates to a grinding machine for circumferenti l grinding and polishing.

Circumferential polishing has a number of advantages relatively to frontal polishing. For example, during circumferential polishing the grinding disk is used up to a lesser extent and more uniformly, and there is a lesser tendency for the clogging up of the pores, etc. However, circumferential grinding and polishing can be used only in cases which are concerned with the grinding edge and not with the surface of the workpiece contacting the circumference of the grinding disk, since this surface acquires the same curvature as the circtu .ference of the disk, due to the fact that in this type of grinding the feed takes place radially to the disk.

An object of the present invention is to improve a grinding and polishing machine of the described type.

Other objects of the present invention will become apparent in the course of the following specification.

In accomplishing the objects of t.e present invention, it was found desirable to arrange the holder of the workiece in such manner that it is capable of swinging, the construction being such that during the grinding the holder moves swingably along the path which contacts the grinding disk.

A particular advantage of the construction wherein the workpiece is so mounted that it is capable of a swinging movement along a path tangential to the grinding disk, in the case of circumferential grinding, is that the surface of the workpiece which is ground or polished during movement along this path has no more curvature or a practically negligible curvature. The radius of the curvature of the polished surface depends upon the radius of the swinging movement. For most constructions it is entirely sufficient when this radius is twice as great as the radius of the polishing disk, whereby the axis of the swinging movement, which extends parallel to the axis of the polishing disk, is located upon the opposed side of the pohshi-g disk. However, it is also possible to guide the workpiece holder in such that the workpiece is reciprocable in a plane tangential to the grinding disk. For that purpose the holder of the workpiece can be re i: bly guided in precisely worked guides. This he advantage that the polished surface will be precisely plane.

According to another embodiment of this invention, the workpiece holder is swngably mounted upon an axis which is parallel to axis of the grinding disk and which is locat d upon the other side of the grinding disk.

in this construction the curvature of the polished surface practically all cases occurring in actual is equivalent to a precisely plane surface. This ctice 1t construction has, however, the great advantage that the lar e circle contacti .2 tne surface of the grindin disk,

it talented Mar. 5, 1953 both provided by the present invention, have the particular advantage that they make it possible to carry out a linear polish of the workpiece, while prior art grinding machines for frontal and circumferential polishing could only carry out a surface polish. Linear polish has by comparison to surface polish the great advantage that the we -iece is heated to a considerably lesser extent than du 5 surface polish, and that the pores of the polishing disk will not be stuffed up. These advantages are of the greatest inportance for practical purposes, since they make it possible to grind or polish steels which are easily damaged by heat, with not too skilled labor, whereby an easy grip of the polishing disk is always assured.

A further advantage of providing a movement along a path tangential to the polishing disk in the case of grinding machines for circumferential grinding, consists in that the workpiece can be set out of contact with the grinding disk to the extent of any desired thickness of chip, whereby this chip thickness gradually diminishes during the movement of the workpiece upon the large circle, irrespective of any high speed with which the feed movement of the workpiece has taken place.

On the other hand, in grinding machines known in prior art the workpiece must be always moved toward the grinding disk very slowly and precisely when the workpiece is being shifted out of contact with the grinding disk. Despite every possible precaution it cannot be always avoided, as far as prior art grinding machines are concerned, that the grinding disk will become flat or unround at the location of contact with the workpiece moved to the extent of a chip thickness.

In the grinding machine of the present invention, however, such damages to the polishing disk are eifectively avoided clue to the gradual contacting of the grinding disk with the workpiece which is moved to it either tangentially or upon a large circle. The grinding disk is then used up uniformly upon its periphery and it does not have to be treated any more with a diamond to restore its roundness, as in the case of prior art grinding machines.

These advantages of the grinding machine of the present invention are not only important for economic reasons, since in prior art the polishing particularly of cutting steels had to be carried out only by skilled labor possessing a good finger touch and decades of experience, but also in that a great saving in grinding disks has become possible. Actual experiment have shown that grinding disks of the machine of the present invention of the same quality, and being subject to the same treatment as in prior art machines, have a life span which is two to three times greater than that of disks in prior art machines, thereby attaining a saving of from 50% to as far as grinding disks are concerned.

A particular advantage of the swinging faculty provided by the present invention resides in that the workpiece can be moved without efiort upon the path presc ibed by the present invention.

it should be noted in this connection that throughout the s ecification and claims the term swingably supported system is meant to define a system which can be reciprocated without any substantial resistance.

According to one embodiment of the present invention, the support about which the oscillatable system containing the workpiece carrier is swingable, is also movable in an atrial direction. This embodiment can be further constructed so that support is movably mounted in guiding rails upon ball bearing strips, so that the entire oscillatable system can be easily shiited perpendicularly to its swinging plane. Due to this arrangement it is possible in the case of workpieces which are considerably narrower than the grinding disk to move them during the swinging movement in the axial direction of the grinding screens =9 disk over the entire width thereof, so that the grinding disk is uniformly used up throughout its circumferential thickness even when grinding workpieces which are narrower than the grinding disk.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawing showing by way of example preferred embodiments of the inventive idea. It will be noted that the individual features hereinafter disclosed can be carried out individually or combined with one or more embodiments.

In the drawing:

FIGURE 1 is a diagrammatic side view illustrating the principle of a grinding machine of the present invention.

FIGURE 2 is a diagram atic side View illustrating a different embodiment.

FIGURE 3 is a diagrammatic side view illustrating yet another embodiment.

FIGURE 4 is a diagrammatic side View illustrating the fourth embodiment.

FIGURE 4a illustrates in diagrammatic side view a somewhat diiferent construction.

FIGURE 5 is a side view of a grinding machine for circumferential grinding constructed in accordance with the principles of the present invention.

FIGURE 6 is a top view of the machine shown in FIG. 5, some parts being shown in section.

FIGURE 7 is a diagrammatic illustration of the movements of a workpiece which is narrower than the grinding disk during the grinding process.

The diagram of FIGURE 1 illustrates the principle according to this invention of the construction of a grinding machine for circumferential grinding, that is, wherein the circumference of the grinding disk engages the workpiece. A support 3 is located above the grinding disk 1, which is rotatab-ly mounted upon a shaft 2. A carrier 4 is mounted upon the support 3, so that it can swing about an axis parallel to the shaft 2 of the grinding disk 1. A workpiece holder 5 is mounted upon the other end of the carrier 4 and is used to carry the workpiece 6. The workpiece hoder 5 is movable in the direction of the feed and is adjustable in the directions of its height and width in the usual manner (not shown), so that it'is possible to subject any desired surface of the workpiece 6 at any desired angle to the grinding and polishing operations. The carrier 4 and the workpiece holder 5 form a system which is oscillatory due to its swingable suspension.

In operation, during the grinding or polishing process, the carrier 4 and the workpiece holder 5 can be easily swung backwards and forwards in the direction of the double arrow 8 relatively to the feed spindle 7, whereby the surface of the workpiece being polished describes a circle about the support 3 which contacts at 9 the circumference of the grinding disk 1.

FIGURE 2 also shows a grinding disk 1 carried by a shaft 2 and a carrier 4 connected with a workpiece holder 5. This construction differs from the one shown in FIGURE 1 in that in the construction shown in FIG. 2, the support 3' for the o-scillatable system consisting of the carrier 4 and the holder 5, is located below the disk 1, so that the workpiece holder 5 carried by the carrier 4 is reciprocably swingable over the grinding disk I in the directions of the double arrow It The angle of oscillation of the oscillatable system 4, 5, is limited by two stops 11. In other respects, the construction and operation of the device shown in FIG. 2 is essentially similar to that shown in FIG. 1.

FIGURE 3 also illustrates a construction having a grinding disk I carried upon the shaft 2 and a carrier 4- provided with a workpiece holder 5. In this construction the carrier 4 is swingable upon a support 3" which is located to the side of the rinding disk 1. Furthermore, in this construction the carrier 4 is rigidly connected or integral with an arm 12 extending beyond the support 3" 4- and carrying a counterweight 13. In this construction the movement of the workpiece during the grinding operation takes place in the directions of the double arrow 14. In other respects this construction is the same as those previously described.

It will be noted that in the constructions shown in FIGURES l, 2 and 3, the workpiece is moved during the grinding operation upon a large circle which contacts the circumference of the grinding disk 1. On the other hand, in the constructions shown in FIGURES 4 and 4a, the workpiece is moved along a tangential line 15 (FIG. 4), contacting the circumference of the grinding disk 1 carried upon the shaft 2.

In the construction shown in FIGURE 4 the holder 5 which carries the workpiece is firmly connected with a supporting rod I6 which is guided in guides 1'7. Any suitable means (not shown) may be used to reciprocate the rod 16 with the holder 5 in the directions of the double arrow. The workpiece 6 will then move along the line 1:; and will contact the disk 1.

FIGURE 4a shows a further development of the construction wherein the workpiece is moved along a tangential line; it illustrates two guides 18, which are swingably mounted at 37' upon a supporting frame 15'. The members 18 operate as tongs and are pivotally interconnected at 19. They are also connected at their pivots by a spring 4%. Furthermore, the members 123 are connected at 19 with levers 21), the free ends of which are guided in a horizontal guide 21. The frame 16 for the workpiece holders has a guide 22 in which the joint 19 is guided. It is apparent that due to this tong-like arrangement the workpiece holder 5 will be reciprocated along a straight line extending tangentially to the circumference of the grinding disk 1.

FIGURE 5 illustrates diagrammatically a grinding machine constructed in accordance with the principle shown in FIG. 3. As illustrated in FIGURE 5, the grinding disk 1 is rotatably mounted upon a shaft 2 and is adapted to engage a steel 6 which is to be polished and which is mounted upon a workpiece holder 5. The holder 5 is mounted upon a carrier 4 in such manner that it can be shifted backwards and forwards in the direction of the double arrow 23 with respect to the feed spindle 7. This mounting of the workpiece holder 5 is best shown in FIG. 6 and it includes two telescoping tubes 24 and 25 as well as dove-tailed guides 26 and 27. The parts which are not covered by the outer tube 24 are enclosed by two bellows 28 and 29.

The carrier 4 consists essentially of two arms which are supported upon bearings 3 in such manner that the carrier 4 can swing about an axis extending parallel to the direction of the shaft 2. For that purpose the bearings 3 are firmly connected with a rail 43 having the shape of an inverted U and movable longitudinally in the directions of the double arrow 43 upon ball bearing strips 38 carried upon a guide rail 31.

A curved arm or tube 32 has one end which is firmly connected to the carrier 4 intermediate the ends of the carrier. The tube 32 extends in a curve over the support 3 and the U-shaped rail 4-1, and has a rear end located behind the guide rail 31 and carrying a counterweight 33. The Weight balancing produced by the weight 33 must be such that the torque resulting from the forces of gravity and acting upon the swingable members 4 and 5 is completely balanced.

In order to eliminate the necessity that the tube or lever arm 32 must have an excessive length or that the counterweight 33 must be quite heavy so as to follow the above stated requirements for the balancing of the forces of gravity, a further lever 34 is provided in the apparatus. The lever 34 is pivotally mounted upon a support 35 and has two arms and 3 4". The arm 34' carries a second count weight 36 whicn can be shifted upon the 34' and placed in any desired position. The second arm 3 carries at its end a member having a guiding slot 37. A pin 38 is located within the slot 37 and is carried upon a bracket 39 which is firmly connected with the carrier 4. Due to this arrangement the arm 34" presses against the pin 33 and this pressure acts against the weight of the carrier 4 and the parts connected therewith. The weights 33 and 36 must be so selected that the swinging system composed of the members 4 and 5 is balanced in each swinging position.

The operation of the machine has been already described in connection with the diagram illustrated in FIGURE 3. Practical experience has shown that the saving in grinding and polishing disks attained by this machine is from 50 to 75% greater than in prior art constructions.

FIGURE 7 illustrates diagrammatically the movements of a workpiece in relation to a grinding disk 1, which is rotatably mounted upon a shaft 2 and which is substantially wider than the workpiece. In that case the workpiece will be moved relatively to the grinding disk 1 along the zigzag path indicated diagrammatically by the numeral 42 in FIGURE 7.

it is apparent that the examples shown above have been given solely by way of illustration and not by way of limitation, and that they are subject to many variations and modifications within the scope of the present invention. All such variations and modifications are to be included within the scope of the present invention.

What is claimed is:

1. A grinding machine for circumferential grinding, said machine comprising, in combination with a rotary grinding disc and a workpiece holder; a pivoted carrier having a freely swingable manually operable end portion connected with said workpiece holder for guiding it along a path tangential to the circumference of said grinding disc and for swinging it back and forth along said path during the grinding, and manually operable means connected with said carrier for shifting said workpiece holder in the direction parallel to the axis of rotation of said rotary grinding disc, and a counterweight carried by an opposite end portion of the carrier for balancing the forces of gravity of the workpiece holder.

2. A grinding machine for circumferential grinding, said machine comprising, in combination with a rotary grinding disc and a workpiece holder; a pivoted freely swlngable manually operable arm having an end portion carrying said workpiece holder for swinging it during the grinding along a path tangential to the circumference of said grinding disc about an axis located beyond that side of the grinding disc which is opposite to the point of contact of the grinding disc with the workpiece, manually operable means connected with said arm for shifting said workpiece holder in the direction parallel to the axis of rotation of said rotary grinding disc, a lever arm connected with the first-mentioned arm and extending in a direction to balance the forces of gravity of said workpiece and of the first-mentioned arm, and a counterweight carried by said lever arm.

3. A grinding machine for circumferential grinding, said machine comprising, in combination with a rotary grinding disc and a workpiece holder; a pivoted freely swingable manually operable arm having an end portion carrying said workpiece holder for swinging it during the grinding along a path tangential to the circumference of said grinding disc about an axis located beyond that side of the grinding disc which is opposite to the point of Contact of the grinding disc with the workpiece, manually operable means connected with said arm for shifting said workpiece holder in the direction parallel to the axis of rotation of said rot ry grinding disc, a curved arm connected with the first-mentioned arm and extending in a direction opposite to that of the first-mentioned arm and beyond the pivot thereof, and a counterweight carried by the second-mentioned arm.

4. A grinding machine for circumferentially grinding a workpiece, said machine comprising, in combination with a rotary grinding disc and a workpiece holder, a pivoted carrier having a freely swingable manually operable end portion carrying said workpiece holder for guiding it alone a path tangential to the circumference of said grinding disc and for swinging it back and forth along said path during the grinding, means connected with said carrier for shifting said workpiece holder in the direction toward the axis of rotation of said rotary grinding disc, a support having downwardly extending lips and supporting said carrier, at frame-carried guide extending parallel to the axis of rotation of said grinding disc, and ballbearing strips between said support and said guide, the lips of said support extending over said guide, a lever pivoted intermediate its ends and having one arm connected with said end portion of the carrier adjacent said workpiece, and a counterweight carried by the other arm of said lever for opposing the forces of gravity of said workpiece and said end portion of the carrier.

References Cited in the file of this patent UNITED STATES PATENTS 43,005 Brown June 7, 1864 53,725 Baker Apr. 3, 1866 327,934 Frech Oct. 6, 1885 507,639 Smith Oct. 31, 1893 1,112,015 Lichter et al Sept. 29, 1914 1,386,638 Loomer Aug. 9, 1921 1,599,405 Bugbee Sept. 14, 1926 1,868,266 Woodsend July 19, 1932 2,056,168 Crowley Oct. 6, 1936 2,697,312 Kallenborn et al Dec. 24, 1954 FOREIGN PATENTS 1,080,246 France May 26, 1954 

1. A GRINDING MACHINE FOR CIRCUMFERENTIAL GRINDING, SAID MACHINE COMPRISING, IN COMBINATION WITH A ROTARY GRINDING DISC AND A WORKPIECE HOLDER; A PIVOTED CARRIER HAVING A FREELY SWINGABLE MANUALLY OPERABLE END PORTION CONNECTED WITH SAID WORKPIECE HOLDER FOR GUIDING IT ALONG A PATH TANGENTIAL TO THE CIRCUMFERENCE OF SAID GRINDING DISC AND FOR SWINGING IT BACK AND FORTH ALONG SAID PATH DURING THE GRINDING, AND MANUALLY OPERABLE MEANS CONNECTED WITH SAID CARRIER FOR SHIFTING SAID WORKPIECE HOLDER IN THE DIRECTION PARALLEL TO THE AXIS OF ROTATION OF SAID ROTARY GRINDING DISC, AND A COUNTERWEIGHT CARRIED BY AN OPPOSITE END PORTION OF THE CARRIER FOR BALANCING THE FORCES OF GRAVITY OF THE WORKPIECE HOLDER. 